1. Field of the Invention
This invention relates to nail making machines. More particularly, it refers to a machine and method for making star shaped nails in cross section employing a skip rolling technique to head the nails.
2. Description of the Prior Art
My prior U.S. patent applications Ser. No. 721,757, filed Apr. 10, 1985; U.S. Ser. No. 001,693, filed Jan. 9, 1987, and Ser. No. 012,099, filed Feb. 6, 1987, describe star shaped fasteners. These fasteners employ substantially less metal than conventional fasteners to make a fastener and have greater strength and holding power in wood. Prior art machines such as shown in U.S. Pat. Nos. 1,579,071, 3,372,413 and 4,637,768 employ cooperative wire cutting elements, pointing dies, cooperative wire grippers and heading devices for heading stock wire while the wire is being held in the grippers. In each of these prior art patents a standard segment of the wire stock is formed, cut and then headed. When such a nail is grooved as in U.S. Pat. No. 4,637,768, there is a limited supply of metal for heading and this causes weakness at the head or a decrease in size of the head. Further, work hardening the wire heading section causes metal fatigue and cracking or splitting of the head. A method is needed which will allow enough metal to be available in grooved nail stock to provide for a normal head to be formed.